Bunch of people who let their hate for McGregor delude them in this thread.
He's arguably top 10 all-time easily. He's very easily top 20 already.
He is a simultaneous two-division champion in the most modern era of MMA, in the UFC. He flat-lined the FW GOAT in 10 seconds basically (lucky yet dominant), he beat the LW champion Alvarez in utterly dominant fashion, he has wins of Holloway, Porier, and Mendes on his resume'. He technically has wins at FW, LW, and WW across 3 divisions.
His legacy is currently better than Khabib's imo, it's very close arguably, and many are prematurely putting Khabib up there in the top 5-7 range all-time right now. McGregor has a better resume'. He does.
I think there's an argument he is top 10 all-time but that's only if we heavily factor in new era / modern era fighting and diminsh older eras aka guys such as Penn, Hughes, Couture, Shogun, etc.
The biggest knocks are: Lack of title defenes, but this is unique and we have to consider that he fought Floyd Mayweather in boxing and then went to LW with a stint at WW in between. And the biggest black mark = the curated path avoiding wrestlers outside of Mendes, which is a legit test elite wrestler who he beat, he avoided or was protected from wrestlers arguably. But he did fight Mendes and Alvarez, then Khabib.
TLDR: Be objective and let go of your opinion of the person. McGregor's FW run is better than Holloway's, he dethroned the GOAT and was unscathed. He then won the LW belt and held two belts, while going to WW and spltting 1-1 with a ~170lb-er in Nate Diaz. Mayweather fight adds something to his UFC legacy too it does, if Fedor had done that everyone would be grabbing vats of vasoline and crates of tissues.